diff --git a/mastodon/Dockerfile.master b/mastodon/Dockerfile.master
index 77aae64..a6302f5 100644
--- a/mastodon/Dockerfile.master
+++ b/mastodon/Dockerfile.master
@@ -19,6 +19,7 @@ RUN apk -U upgrade \
     ffmpeg \
     file \
     git \
+    icu-libs \
     imagemagick \
     libpq \
     libressl \
@@ -36,6 +37,7 @@ RUN apk -U upgrade \
     su-exec \
  && apk add -t build-dependencies \
     build-base \
+    icu-dev \
     libffi-dev \
     libxml2-dev \
     libxslt-dev \
@@ -51,7 +53,7 @@ RUN apk -U upgrade \
  && bundle install --deployment --clean --no-cache --without test development \
  && npm install -g npm@3 && npm install -g yarn \
  && yarn --ignore-optional --pure-lockfile \
- && SECRET_KEY_BASE=$(rake secret) rake assets:precompile \
+ && SECRET_KEY_BASE=$(rake secret) SMTP_FROM_ADDRESS= rake assets:precompile \
  && npm -g cache clean && yarn cache clean \
  && mv public/assets /tmp/assets && mv public/packs /tmp/packs \
  && apk del build-dependencies \